Use FFmpeg for image format conversion and image scaling/sws_scale/linux/c++/c/rgb-yuv420__linux

The use of ffmpeg for image Data format conversion and image scaling applications, mainly used in the Swscale.h file three functions, respectively:

struct Swscontext *sws_getcontext (int srcw, int srcH, enum Avpixelformat Srcformat,
int DSTW, int dsth, enum Avpixelformat Dstformat,
int flags, Swsfilter *srcfilter,
Swsfilter *dstfilter, const double *param);

int Sws_scale (struct swscontext *c, const uint8_t *const),

const int srcstride[], int srcslicey, int srcsliceh,
uint8_t *const dst[], const int dststride[]);

void Sws_freecontext (struct swscontext *swscontext);

The sws_getcontext function can be considered an initialization function, and its parameter definitions are:

int Srcw,int SrcH is the height and width of the original image data;

int Dstw,int Dsth is high and wide for output image data;

Enum Avpixelformat Srcformat is the type of input and output picture data; eg:av_pix_fmt_yuv420, pav_pix_fmt_rgb24;

int flags is the scale algorithm type, eg:sws_bicubic, Sws_bicublin, Sws_point, Sws_sinc;

Swsfilter *srcfilter, Swsfilter *dstfilter,const double *param can be used without tube, all is null;

The sws_scale function is an execution function, and its parameter definitions are:

struct Swscontext *c is the value returned by the Sws_getcontext function;

The const uint8_t *const srcslice[],uint8_t *const dst[] is an array of buffer pointers for each color channel of the input and output image data;

const int Srcstride[],const int dststride[] An array of bytes stored per line for each color channel of the input and output image data;

int Srcslicey is a line-by-row scan from the first number of input image data, usually set to 0;

int SRCSLICEH is the number of rows that need to be scanned, usually the height of the input image data;

the sws_freecontext function is the End function, and its parameter is the value returned by the Sws_getcontext function;

Sample code: rgb24_2_rgb24/1600*1200-352*288

. h

#ifndef int64_c
#define Int64_c
#define Uint64_c
#endif

extern "C"
{
#include "libswscale/ Swscale.h "
}
struct imginfo
{
    unsigned int height;
    unsigned int width;
    unsigned long buffersize;
    unsigned char *bufferptr;
} Rawdate;

. cpp

    int nsrch = Rawdata.height;   1200 int NSRCW = Rawdata.width;   1600 int ndsth = Resized_hight;   258 int NDSTW = resized_width; 352 uint8_t *psrcbuff[3] = {rawdata.bufferptr, rawdata.bufferptr + NSRCW * nsrch, rawdata.bufferptr + NSrcW * n
    SrcH * 2}; uint8_t *pdstbuff[3] = {presizeddata->bufferptr, presizeddata->bufferptr + NDSTW * NDstH, pResizedData->
       
    Bufferptr + NDSTW * ndsth * 2};
    int nsrcstride[3];
    
    int ndststride[3];
    	for (int i=0; i<3; i++) {Nsrcstride[i] = NSRCW * 3;
    Ndststride[i] = NDSTW * 3;
    
    } swscontext* M_pswscontext; M_pswscontext = Sws_getcontext (NSRCW, Nsrch, Av_pix_fmt_rgb24, NDSTW, Ndsth, Av_pix_fmt_
                                  
    RGB24, sws_sinc, NULL, NULL, NULL);
    	if (NULL = = M_pswscontext) {printf ("FFmpeg get Context error!\n"); RetUrn false;
              
    Sws_scale (M_pswscontext, Psrcbuff, nsrcstride, 0, Nsrch, Pdstbuff, ndststride); Sws_freecontext (M_pswscontext);

Sample code: rgb24_2_yuv420/1600*1200-352*288

. cpp

    int nsrch = rawdata->height;    1200 int NSRCW = rawdata->width;    1600 int ndsth = Resized_hight;    The resized_width int NDSTW =;  352 uint8_t *psrcbuff[3] = {rawdata->bufferptr, rawdata->bufferptr + NSRCW * nsrch, Rawdata->bufferptr
    + NSRCW * Nsrch * 2}; uint8_t *pdstbuff[3] = {resizedyuvdata->bufferptr, resizedyuvdata->bufferptr + NDSTW * NDstH, resizedYuvData->
       
    Bufferptr + NDSTW * ndsth * 5/4};
    int nsrcstride[3];
    
    int ndststride[3];
    for (int i=0; i<3; i++) {Nsrcstride[i] = NSRCW * 3;
    } ndststride[0] = NDSTW;
    NDSTSTRIDE[1] = NDSTW/2;
    
    NDSTSTRIDE[2] = NDSTW/2;
    
    swscontext* M_pswscontext; M_pswscontext = Sws_getcontext (NSRCW, Nsrch, Av_pix_fmt_rgb24, NDSTW, Ndsth, Av_pix_fmt_
                           yuv420p, sws_sinc, NULL, NULL, NULL);       
    if (NULL = = M_pswscontext) {printf ("FFmpeg get Context error!\n");
    return false;
              
    Sws_scale (M_pswscontext, Psrcbuff, nsrcstride, 0, Nsrch, Pdstbuff, ndststride);	 Sws_freecontext (M_pswscontext);